The major function of absorbent articles such as disposable diapers and incontinent briefs or undergarments is to absorb and contain body exudates. Such articles are thus intended to prevent body exudates from soiling, wetting, or otherwise contaminating clothing or other articles, such as bedding, that come in contact with the wearer. The most common mode of failure for such products occurs when body exudates leak out of the gaps between the article and the wearer's legs or waist to adjacent clothing because they are not immediately absorbed within the article and the absorbent article is not able to sustain a good fit on the wearer such that gaps are created allowing the exudates to leak out of the article. For example, urine tends to be deposited onto the topsheet in gushes such that the urine migrates to the gaps between the article and the wearer where it can come in contact with clothing or other articles and be absorbed by these articles. Additionally, loose fecal material that is not easily absorbed by the absorbent article tends to "float" on the body-contacting surface and work its way past the gaps between the article and the legs or waist of the wearer.
Contemporary disposable diapers have a topsheet, a backsheet, an absorbent core, and one or more cuffs, typically elastic cuffs, positioned to contact the legs and/or waist of the wearer. These elastic cuffs prove effective generally to prevent wicking and overflow from the fluid laden diaper to clothing contacting the edges of the diaper in that the elastic cuffs present a barrier between the edge of the diaper and the contacting clothing, and generally in addition, provide a gasketing action about the legs or waist of the wearer to maintain a seal about the leg or waist and minimize gapping. However, because the forces generated by the elastic members are concentrated along a narrow area resulting in high localized pressures, such elastic cuffs have an increased tendency to indent and mark the skin of the wearer. These skin effects are particularly acute for products worn by infants and incontinent elderly adults due to the tenderness of their skin and its sensitivity to even slight pressures or rubbing actions. These skin effects are even further accentuated due to the occlusion of the skin caused by such products. The occlusion of the skin by the diaper can potentially lead to skin overhydration. As a result, overhydrated skin is more susceptible to damage from abrasion due to rubbing caused by normal wearer movements and contact with the elastic cuffs. It is also generally known that overhydrated skin is more susceptible to skin disorders, including diaper rash, erythema, heat rash, abrasion, pressure marks, and skin barrier loss. The reduced barrier efficiency of abraded, overhydrated skin can further cause an increase in diaper rash. (21 CFR .sctn. 333.503 defines diaper rash as "[a]n inflammatory skin condition in the diaper area (perineum, buttocks, lower abdomen, and inner thighs) caused by one or more of the following factors: moisture, occlusion, chafing, continued contact with urine or feces or both, or mechanical or chemical irritation.") To address the concerns of skin disorders associated with wearing diapers and other absorbent articles, the caregiver or wearer often applies skin protective and/or therapeutic products to the buttocks, genitals, anal and/or other regions before placing the absorbent article on the wearer. This procedure usually involves the caregiver applying the skin protective product to their hands, and then wiping the same on the skin of the wearer. To eliminate the need for this wasteful, messy, time-consuming, and easily forgotten procedure, there have been attempts to prepare absorbent articles which contain a skin care substance on the article's topsheet.
The art has further responded to detrimental skin effects due to using cuffs by providing absorbent articles having cuffs with a skin care composition disposed on the cuffs to provide improved skin care benefits, particularly in skin regions in contact with the cuff during use. Such skin care compositions are transferable to the wearer's skin to provide these skin benefits. Particularly useful skin care compositions and absorbent articles with cuffs having such skin care compositions disposed thereon are described in U.S. patent application Ser. No. 08/962,310, filed in the name of Schulte, et al, on Oct. 31, 1997.
However, while such skin care compositions and absorbent articles provide substantial skin care benefits, further improvements are needed. For example it is important that the skin care composition not inhibit the functionality of the cuff in the absorbent article. However, oleaginous components of the skin care composition can diffuse from the body surface of the cuff to an interior surface where such components can come into contact with the construction adhesive used to assemble the cuff. If such contact occurs, the oleaginous components can plasticize the adhesive causing a modulus reduction therein with resulting creep due to the contractive force of the elastic members within the cuffs. Such creep can ultimately cause separation of the cuff material and the elastic member with a resulting loss of contractive force and increase in leakage around the cuff.
While the art has, until the aforementioned in U.S. patent application Ser. No. 08/962,310, failed to recognize the value of applying a skin care composition to cuffs in an absorbent article, the interaction between construction adhesives for absorbent articles and topically applied lotions and ointments has been recognized. For example, PCT application Serial No. WO 97/38739, published in the names of Zacharias, et al on Oct. 23, 1997, describes elastic composites assembled using an adhesive said to have desirable oil resistance and processing properties. Claimed are elastic composites comprising two substrates wherein the first substrate is attached to the second substrate using an adhesive which has a minimum dynamic elastic modulus both before and after exposure to a commercial baby lotion, a maximum viscosity at a first temperature, and a minimum viscosity at a second lower temperature. While elastic composites made using such adhesives may have improved resistance to oleaginous components of topically applied lotions during the relatively short exposure time an absorbent article is worn (e.g. a diaper is typically worn for about three hours), improvements are needed. For example, the temperature required to achieve an adhesive viscosity low enough for use in typical glue spray apparatus may cause the adhesive temperature to be too high for use with thermally sensitive absorbent article components (e.g. low basis weight films used for backsheets).
Thus there is a need for improved construction adhesives for absorbent articles. In particular, there is a need for adhesives that have improved resistance to oleaginous components of skin care compositions for assembly of absorbent articles that may have such skin care compositions disposed thereon and for adhesives that do not unduly limit the choice of materials that may be used as components of such absorbent articles or process flexibility when applying the adhesives in the assembly of the absorbent article. These and other needs are addressed by the invention described below.